suggestion for a select all checkbox ?

Prototype (the javascript library that ships with Rails) is really incredible and can help you out here.  What you need is to make sure your checkboxes have a class attribute set.  I'll assume your form is called 'my_form' (<form id="my_form" action="">) and the checkboxes have the class 'check'.

Here's a button that should do the trick:

<input type='submit' value='Check All' onClick="$$('#my_form input.check').each(function(box){box.checked=true});return false;" />

That's untested, but it should work.

I can't seem to get this to work,  I click the butotn and nothing happens.  I don't get any erorrs in my javascript console or anything.  I'm trying to use it with a checkbox instead of a button, but I couldn't ge the button to work either.  I have the the tag in my header

<%= javascript_include_tag :defaults %>

<form name="my_form" action="">
<h1>Filter recipients</h1>
<p>Select the contacts you'd like to publish to and press publish when ready...</p>
<h3>User Type</h3>  
<table><tr><td colspan="3">
<input type="checkbox" name="types[]" class="check" value="All" onClick="$$('#my_form input.check').each(function(box){box.checked=true})">All
</td></tr><tr>
<% i = 0 %>
<% for user_type in @user_types %>
<td><input type="checkbox" class="check" name="types[]" value="<%= user_type.name %>" /><label for="filter_types"><%= user_type.name %></td>
<% i = i + 1 %>
<% if i > 2 %>
<% i = 0 %>
</tr><tr>
<% end %>
<% end %>

Solved it

<input type="checkbox" name="types[]" value="All" onClick="$$('#my_form input.check').each(function(box){box.checked=!box.checked})">All

Works great thanks danger!